They could be abolished sooner than first thought (Image: Western Mail Archive)

While the Wales Office said it couldn't confirm when an announcement will be made, a possible platform could be Mr Cairns' speech to the Conservative Party annual conference in Birmingham which runs from September 30 to October 3.

If such an announcement was made at conference, it is unlikely that their abolition would be with immediate effect.

Instead, notice could be served of tolls being removed in late November or early December, potentially coinciding with the date of the next Budget.

Although the date of Phillip Hammond's Budget has not yet been confirmed by the UK Treasury, it is expected towards the end of November.

Some 25 million journeys are made across the two bridges annually. Those using using them daily could save about £1,400 a year.